This invention relates to a novel molding method and apparatus and more particularly relates to a new multiaxis rotational molding method and apparatus.
The production of man-made plastic and resin articles is an industry that utilizes a high degree of automatically controlled continuous processing. However, for units of appreciable size, batch processing still is the rule rather than the exception. For example, in the production of fiberglass structures such as boats, it is customary to construct the hulls by hand. A plurality of resin and fiberglass layers are sequentially laminated on an open mold or a plurality of mixed resin/chopped fiber coatings are applied over the mold.
Such hand building procedures require a great amount of labor, supervision and continuous inspection to insure that a reasonable level of quality is achieved. This greatly increases the cost of the product.
The applicant""s earlier patents listed above provide a novel method and apparatus for producing both large and small molded structures continuously. The apparatus includes unique combinations of components to produce a wide variety of different products. Achieving this capability requires a major capital investment. Also, personnel to utilize the broad parameters of the apparatus normally are highly trained and experienced.
The present invention provides a novel molding method and apparatus which not only overcome the deficiencies of present technology but also provide features and advantages not found in earlier expedients. The multiaxis rotational molding method and apparatus of the invention provide a means for the production of a large number of uniform high quality products rapidly and efficiently.
The multiaxis rotational molding apparatus of the present invention is simple in design and can be produced relatively inexpensively. Commercially available materials and components can be utilized in the manufacture of the apparatus. Conventional metal fabricating procedures can be employed by semi-skilled labor in the manufacture of the apparatus. The apparatus is durable in construction and has a long useful life with a minimum of maintenance.
The apparatus of the invention can be operated by individuals with limited mechanical skills and experience. A large number of high quality molded structures can be produced rapidly by such persons safely and efficiently with a minimum of supervision.
The molding method and apparatus of the invention can be modified to mold a wide variety of new structures. Variations both in product configuration and composition can be attained simply and conveniently with the method and apparatus of the invention. Even with such variations, uniformity and quality of product dimensions and shapes still are maintained without difficulty.
A novel method of the present invention for continuously forming integrally molded structures includes the steps of rotating a plurality of independently movable multisection mold assemblies about a plurality of axes. A first freshly formed polymerizable mixture is supplied to a first mold assembly. The first polymerizable mixture is flowed over surfaces of a first enclosed mold cavity within the first mold assembly while selectively heating at least one of the mold sections of the first mold assembly in a preselected heating profile. The flowing of the first mixture over the first mold cavity surfaces, the heating of the mold section and the formation of a first resin therefrom are monitored.
The first polymerizable mixture is supplied to a second mold assembly. The first polymerizable mixture is flowed over surfaces of a second enclosed mold cavity within the second mold assembly while selectively heating at least one of the mold sections of the second mold assembly in a preselected heating profile. Simultaneously therewith, a freshly formed second polymerizable mixture is supplied to the first mold assembly. The second polymerizable mixture is flowed over the first resin within the first mold cavity while selectively heating at least one of the mold sections of the first mold assembly in a preselected heating profile. The flowing of the first and second polymerizable mixtures within the first and second mold cavities, the heating of the mold sections and the formation of first and second resins therefrom are monitored.
The first polymerizable mixture is supplied to a third mold assembly. The first polymerizable mixture is flowed over surfaces of a third enclosed mold cavity within the third mold assembly while selectively heating at least one of the mold sections of the third mold assembly in a preselected heating profile. Simultaneously therewith, the second polymerizable mixture is supplied to the second mold assembly. The second polymerizable mixture is flowed over the first resin within the second mold assembly while selectively heating at least one of the mold sections of the second mold assembly in a preselected heating profile. The flowing of the first and second polymerizable mixtures within the second and third mold cavities, the heating of the mold sections and the formation of first and second resins therefrom are monitored.
The supplying of the first and second polymerizable mixtures succeeding mold assemblies and the flowing of the mixtures into the respective mold cavities while selectively heating the mold sections is continued until all of the mold assemblies have received the mixtures. Also the monitoring of the flowing of the mixtures, the heating of the mold sections and the formation of resins therefrom are continued.
The rotation of the mold assemblies is continued throughout the steps of the continuous molding operation while monitoring individually each axis rotation of the mold assemblies. The monitored flowing of each mixture, the monitored heating of the mold sections and the monitored formation of each resin are coordinated with each monitored axis rotation in a preselected profile to form the integrally molded structures of the first and second resins.
The mold sections of each mold assembly are separated after the integrally molded structure therein has achieved structural integrity within the mold cavity. The structure is removed from the separated mold sections and the steps are repeated to form a multiplicity of the integrally molded structures on a continuing basis. Advantageously, the integrally molded structures are separated from the mold assembly by cooling the molded sections.
The method of the invention preferably includes the steps of flowing at least one of the polymerizable mixtures into a mold cavity and rotating the cavity only a sufficient amount to coat the first mold section before heating the coated mold section to set the coating in place. Thereafter, the rotation of the mold cavity is continued to coat an adjacent second mold section followed by the heating of the second coated section to set the coating adhering thereto. Further rotation coats each succeeding mold section and the heating thereof results in the formation of an integrally molded product within the mold cavity. Subsequent cooling of the mold sections frees the molded structure from the mold assembly.
Advantageously, the mold assembly is transferred to an adjacent mold receiving station prior to separating the mold sections and removing the molded structure. Thereafter, the mold assembly is returned to a molding position for repeating the method of the invention. A plurality of mold assemblies may be provided for each molding position so molding can continue while other mold assemblies are being opened and being prepared for another molding cycle.
If desired, solid particles may be introduced into the mold cavity of each mold assembly and the particles distributed in a preselected configuration before supplying the first polymerizable mixture to the respective mold assembly. Also, micro spheres may be introduced into at least one of the polymerizable mixtures prior to molding.
Benefits and advantages of the novel multiaxis rotatable molding method and apparatus of the present invention will be apparent from the following description and the accompanying drawings in which: